Mortise locks which employ automatic dead bolts are often used in hotels and the like so that a guest need not independently and manually throw the dead bolt. The automatic dead bolt feature also increases the security of the guest in the room. There is presently a need in the industry for a mortise lock with an automatic dead bolt feature which operates smoothly and efficiently with a maximum of simplicity.
As previously mentioned, it is known in the art to have a mortise lock which employs an automatic dead bolt. For example, such a mortise lock is disclosed in Krings patent 298,542 granted Dec. 4, 1883. In addition, various types of triggers have been employed in the prior art for sensing a strike plate when a door is closed and thereby releasing the dead bolt so it may be moved to its extended position. Some examples of prior art triggers may be found in the Krings '542 patent as mentioned above and also in the O'Keefe patent 416,181 granted Dec. 3, 1889 and the Young et al patent 2,519,808 granted Dec. 22, 1950. Finally, it is also known to employ a ratcheted stop means in conjunction with the trigger for the automatic dead bolt as disclosed in the Raymond et al application, U.S. Ser. No. 342,144 entitled "Spring Loaded Dead Bolt Assembly", now abandoned.
Mortise lock assemblies which employ automatic dead bolts in the prior art often have problems with retaining the dead bolt in its retracted position and also with inadvertent releasing of the dead bolt which causes the dead bolt to fly out to its extended position before the door is closed.